MXL 20-80Teeth Timing Belt Pulleys Pitch 2.032mm AF-type With Keyway Width 7mm

The tooth count determines your drive ratio. Divide the driven pulley teeth by the drive pulley teeth to get the ratio. For a 1:1 ratio use matching tooth counts on both pulleys. For speed reduction (more torque), use a larger driven pulley. For speed increase, use a smaller driven pulley. Common CNC and 3D printer setups use 20 T drive pulleys paired with larger idlers, but this product starts at 26 T — verify your design requirements before ordering.

Measure your motor shaft diameter with calipers before ordering. NEMA 17 steppers typically have a 5 mm shaft, but this pulley's smallest bore is 8 mm — you would need a shaft adapter or a different pulley series for 5 mm shafts. NEMA 23 motors commonly use 6.35 mm (1/4 in) or 8 mm shafts, making the 8 mm bore variant a direct fit for 8 mm shafts. Always confirm your shaft diameter before selecting a variant.

Keyway dimensions are matched to bore size: the 8 mm and 10 mm bores use a 3×1.4 mm keyway, the 12 mm and 12.7 mm bores use a 4×1.8 mm keyway, and the 14 mm and 15 mm bores use a 5×2.3 mm keyway. The keyway option is shown in the "Keyway & Amount" variant selector. Make sure your shaft has a matching keyway cut, or use a set screw collar if your shaft is plain.

No. This pulley is designed exclusively for MXL profile timing belts with a 2.032 mm pitch. GT2 belts have a 2 mm pitch with a different tooth profile geometry, and HTD belts use a rounded tooth form — neither is interchangeable with MXL. Using a mismatched belt will cause skipping, accelerated wear, and loss of positional accuracy. Always pair MXL pulleys with MXL belts.

Aluminum alloy pulleys are well-suited for light-to-medium duty continuous operation such as 3D printer axes, small CNC routers, and conveyor drives running at moderate speeds and loads. For heavy industrial loads, high-torque drives, or abrasive environments, a steel pulley would be more appropriate. The AF-type keyway provides positive torque transfer, reducing the risk of slipping under normal operating conditions.

Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop conditions. It is not recommended for outdoor exposure, salt spray, or highly acidic/alkaline environments without additional surface treatment. For humid but indoor environments, the pulley should perform reliably over its service life without special maintenance.

All variants in this listing include a pre-cut keyway — there is no plain bore option in this series. If your shaft does not have a keyway, you can still use the pulley by leaving the keyway slot empty and securing the pulley with a set screw against the shaft flat or using a shaft collar. However, for best torque transfer and concentricity, a matching keyed shaft is recommended.